
package com.heimali.happyreader.utils;

import android.text.TextUtils;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class AESUtils {
    public static final String TAG = "AESUtils";

    public static String encrypt(String seed, String cleartext) throws Exception {      
        return cleartext;
        
//        if (TextUtils.isEmpty(seed) || TextUtils.isEmpty(cleartext)) {
//            return null;
//        }
//        
//        byte[] rawKey = getRawKey(seed.getBytes());      
//        byte[] result = encrypt(rawKey, cleartext.getBytes());      
//        return toHex(result);      
    }      
          
    public static String decrypt(String seed, String encrypted) throws Exception {
        return encrypted;
        
//        if (TextUtils.isEmpty(seed) || TextUtils.isEmpty(encrypted)) {
//            return null;
//        }
//        
//        byte[] rawKey = getRawKey(seed.getBytes());      
//        byte[] enc = toByte(encrypted);      
//        byte[] result = decrypt(rawKey, enc);      
//        return new String(result);      
    }      
     
    private static byte[] getRawKey(byte[] seed) throws Exception {      
        KeyGenerator kgen = KeyGenerator.getInstance("AES");      
        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");      
        sr.setSeed(seed);      
        kgen.init(128, sr); // 192 and 256 bits may not be available      
        SecretKey skey = kgen.generateKey();      
        byte[] raw = skey.getEncoded();      
        return raw;      
    }      
     
          
    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {      
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
        Cipher cipher = Cipher.getInstance("AES");      
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);      
        byte[] encrypted = cipher.doFinal(clear);      
        return encrypted;      
    }      
     
    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {      
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
        Cipher cipher = Cipher.getInstance("AES");      
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);      
        byte[] decrypted = cipher.doFinal(encrypted);      
        return decrypted;      
    }      
     
    public static String toHex(String txt) {      
        return toHex(txt.getBytes());      
    }      
    public static String fromHex(String hex) {      
        return new String(toByte(hex));      
    }      
          
    public static byte[] toByte(String hexString) {      
        int len = hexString.length()/2;      
        byte[] result = new byte[len];      
        for (int i = 0; i < len; i++)      
            result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();      
        return result;      
    }      
     
    public static String toHex(byte[] buf) {      
        if (buf == null)      
            return "";      
        StringBuffer result = new StringBuffer(2*buf.length);      
        for (int i = 0; i < buf.length; i++) {      
            appendHex(result, buf[i]);      
        }      
        return result.toString();      
    }      
    private final static String HEX = "0123456789ABCDEF";      
    private static void appendHex(StringBuffer sb, byte b) {      
        sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));      
    }
}
